I've got a 2003 civic LX, 5spd manual, 130k on the clock.

It burns a bit of oil-- has since I bought it at 110k. It loses a bit of coolant, as well. It's overheated (about 3/4 the way up the temp gauge) maybe twice in 6 months.

Compression test results from 2 different test kits on 1, 2, 3, 4 were as follows:

225, 160, 220, ~225
180, 110, 180, 180 (new rental tool from Autozone.)

Not sure why 2 different gauges are giving different readings but the pattern is the same.

Now the odd part: I let it idle for 20 minutes and did a Combustion Gas Leak test on the radiator. It tested fine. I always have heat on the highway and only have heat at idle about half the time. I was getting a random misfire on Cylinder 4, thought it was the coil, swapped it around, and misfire went to Cylinder 2. I bought a new coil and still rarely (only shortly after starting, and only sometimes) get the misfire on cylinder 2.

There's no oil in the coolant, or vice versa. No bubbling in the coolant from gases, either. If I rev the engine, the coolant jumps, but that's all. But I'm pretty sure the coolant was overflowing or getting lost somewhere.

I hooked up my Actron scanner to read the live data. Coolant temps ranging from 185-205. Radiator fan doesn't kick on until about 205, which is concerning.

I'm thinking there may be multiple issues at play here, but for the main thing, I'm not convinced it's a head gasket.

Any suggestions or anything? Any insight would be most appreciated.

 

Sounds like you do have at least two issues. The misfire and lack of compression in cylinder 2 could be a lose valve. Have you checked valve clearences?

Overheating: where does the coolant leak from? A restriction in the system would cause it to overflow from the reservoir and overheating once coolant is low. Restriction could be in radiator, heater core, thermostat stuck closed.